JP6989039B1 - Water treatment agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment agent in which decomposition of a sulfonated pyrene compound is suppressed and a degree of freedom in pH is high. A water treatment agent containing a (meth) acrylic acid-based polymer containing a structural unit derived from (meth) acrylic acid and a sulfonated pyrene-based compound having a pH of more than 2 and less than 12. [Selection diagram] None

Description

The present invention relates to a water treatment agent used in a cooling water system, which comprises a (meth) acrylic acid-based polymer and a sulfonated pyrene-based compound as a tracer substance.

Conventionally, in the cooling water system, anticorrosive agents and anti-scale agents have been used to prevent corrosion and scale of metal members used in the cooling water system, and to prevent the generation of microorganisms such as bacteria and algae in the cooling water system. , Various water treatment agents containing components having a chemical effect such as a bactericidal agent and an algae-killing agent (hereinafter, also referred to as effective components) are used.
In a cooling water system to which a water treatment agent used for such a purpose is added, in order to exhibit a high chemical effect and maintain the effect, water treatment is continuously performed at key points of the cooling water distribution channel. The concentration of the active ingredient derived from the agent is controlled.

Ideally, the concentration of the effective component derived from the added water treatment agent is controlled by measuring the concentration of the effective component itself, but it may be difficult to measure the concentration easily and quickly depending on the type of the effective component. In addition, several kinds of active ingredients may be used in combination, in which case it is difficult to accurately measure the concentration of each active ingredient.

To solve this problem, we propose a method to control the concentration of the active ingredient in the cooling water by adding a water treatment agent containing the tracer substance to the cooling water system together with the active ingredient and measuring the tracer substance in the cooling water. Has been done.
For example, in Patent Document 1, a water-soluble polymer having a carboxylic acid or a carboxylic acid salt having a drug effect as a monomer unit as a water treatment agent capable of stably carrying out concentration control, and a sulfonated pyrene compound as a tracer substance. A water treatment agent having a pH adjusted to 2 or less has been proposed. Further, in Patent Document 2, as a water treatment agent capable of stably carrying out concentration control, a water-soluble polymer having a carboxylic acid or a carboxylate having a drug effect as a monomer unit, and a sulfonated pyrene compound as a tracer substance. A water treatment agent having a pH adjusted to 12 or more has been proposed.

Japanese Unexamined Patent Publication No. 2015-188813 JP-A-2015-188814

Since the sulfonated pyrene-based compound contained in the water treatment agents described in References 1 and 2 is a fluorescent substance, the concentration of the sulfonated pyrene-based compound can be measured by using a fluorometer. Is. Therefore, if the water treatment agent added to the cooling water system contains the same compound, the concentration of the sulfonated pyrene compound in the cooling water can be measured on the spot by installing a fluorometer at a key point in the flow path of the cooling water. From that value, the concentration of the active ingredient derived from the water treatment agent in the cooling water can be calculated.

However, the sulfonated pyrene-based compound is decomposed under irradiation with sunlight, particularly ultraviolet rays, and when it is dissolved in water together with a polymer having a drug effect, the decomposition is further accelerated. In addition, in cooling tower equipment that is generally used by installing it in an environment exposed to sunlight such as outdoors or on the roof of a building, the storage section of sulfonated pyrene compounds and the supply route to cooling water are highly advanced. Unless shaded, the concentration of the active ingredient obtained from the measurement results of the sulfonated pyrene compound will be unreliable. To deal with such problems, the pH of the water treatment agent should be 2 or less so that the sulfonated pyrene compound does not decompose even under sunlight and the decomposition does not accelerate even if it is dissolved in water together with a polymer having a chemical effect. It is necessary to adjust to an acidic solution or an alkaline solution of 12 or more, and there is a problem that the degree of freedom of pH of the water treatment agent is low.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a water treatment agent in which decomposition of a sulfonated pyrene compound is suppressed and a degree of freedom in pH is high. Is.

In the present invention, by using a (meth) acrylic acid-based polymer containing a structural unit derived from (meth) acrylic acid in combination with a sulfonated pyrene-based compound, decomposition of the sulfonated pyrene-based compound is suppressed and the pH is suppressed. It is based on the finding that it is possible to provide a water treatment agent having a high degree of freedom.

That is, the present invention provides the following [1] to [7].
[1] A (meth) acrylic acid-based polymer containing a structural unit derived from (meth) acrylic acid,
Including sulfonated pyrene compounds
A water treatment agent having a pH of more than 2 and less than 12.
[2] The water treatment agent according to the above [1], wherein the sulfonated pyrene compound is at least one selected from pyrenetetrasulfonic acid and pyrenetetrasulfonate.
[3] The water treatment agent according to the above [1] or [2], wherein the sulfonated pyrene compound is a 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt.
[4] The (meth) acrylic acid-based polymer is a polymer containing a structural unit derived from (meth) acrylic acid and a structural unit derived from a sulfonic acid group-containing compound, and a salt thereof. The water treatment agent according to any one of [3].
[5] The (meth) acrylic acid-based polymer has a structural unit derived from at least one selected from acrylic acid and a salt thereof, and at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and a salt thereof. The water treatment agent according to any one of the above [1] to [4], which is a polymer containing a structural unit derived from the above and a salt thereof.
[6] The above-mentioned [1] to [5], wherein the (meth) acrylic acid-based polymer is a polymer containing a structural unit derived from (meth) acrylic acid and a structural unit derived from an allyl ether compound, and a salt thereof. ] The water treatment agent according to any one of.
[7] The (meth) acrylic acid-based polymer is selected from a structural unit derived from at least one selected from acrylic acid and a salt thereof, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid and a salt thereof. The water treatment agent according to any one of the above [1] to [6], which is a polymer containing at least one structural unit and a salt thereof.

According to the present invention, it is possible to provide a water treatment agent in which the decomposition of the sulfonated pyrene compound is suppressed and the pH has a high degree of freedom.

Changes in residual fluorescence intensity over time in Example 1 Changes in residual fluorescence intensity over time in Example 2 Changes in residual fluorescence intensity over time in Example 3

Hereinafter, the present invention will be described in detail.
In addition, in this specification, "(meth) acrylic" means acrylic and / or methacrylic, and the same applies to the notation of "(meth) acrylate" and "(meth) acryloyl".

[Water treatment agent]
The water treatment agent of the present invention contains a (meth) acrylic acid-based polymer containing a structural unit derived from (meth) acrylic acid, and a sulfonated pyrene-based compound. Further, the water treatment agent of the present invention is characterized in that the pH is more than 2 and less than 12, and the degree of freedom of pH is high.
Further, the water treatment agent of the present invention is used for the purpose of controlling the concentration of the effective component derived from the water treatment agent in the cooling water system, and also prevents corrosion and scale of metal members used in the cooling water system, and in the cooling water system. For the purpose of at least one selected from the prevention of the generation of microorganisms such as bacteria and algae in the water, industrial water or tap water used as cooling water or treated water obtained by degassing, softening or filtering these. It is to be added. The water treatment agent of the present invention may be used in combination with a water treatment agent different from the water treatment agent of the present invention.

From the viewpoint of ease of pH adjustment, the water treatment agent of the present invention preferably has a pH of 3 to 10, more preferably pH 4 to 9, and even more preferably pH 5 to 8.

<(Meta) acrylic acid polymer>
In the present invention, the (meth) acrylic acid-based polymer is a polymer containing a structural unit derived from (meth) acrylic acid.
By including the (meth) acrylic acid-based polymer in the water treatment agent, it is possible to suppress the decomposition of the sulfonated pyrene-based compound in a wide range where the pH of the water treatment agent is more than 2 and less than 12. That is, the degree of freedom in the pH of the water treatment agent can be increased.
The (meth) acrylic acid-based polymer is particularly limited as long as it is an effective component that suppresses the decomposition of the sulfonated pyrene-based compound and has effects such as corrosion prevention and scale prevention of the metal member used in the cooling water system. However, from the viewpoint of further suppressing the decomposition of the sulfonated pyrene-based compound, at least one selected from the following (A) to (C) is preferable.
(A) Polymer consisting only of structural units derived from (meth) acrylic acid and salts thereof (B) Polymers containing structural units derived from (meth) acrylic acid and structural units derived from sulfonic acid group-containing compounds and A polymer containing a structural unit derived from the salt (C) (meth) acrylic acid and a structural unit derived from an allyl ether compound, a structural unit thereof derived from the salt (D) (meth) acrylic acid, and a sulfonic acid group. Polymers and salts thereof containing structural units derived from contained compounds and structural units derived from substituted acrylamide compounds.

Examples of the (meth) acrylic acid in (A) to (D) include acrylic acid, methacrylic acid, and salts thereof. Examples of the salt of the (meth) acrylic acid include sodium salt, potassium salt, ammonium salt and the like. Among these, acrylic acid (AA) is preferable from the viewpoint of further suppressing the decomposition of the sulfonated pyrene compound. These can be used alone or in combination of two or more.

Examples of the sulfonic acid group-containing compound in (B) and (D) include 2- (meth) acrylamide-2-methylpropanesulfonic acid and a salt thereof, (meth) allylsulfonic acid, vinylsulfonic acid, styrenesulfonic acid and Examples thereof include the salt thereof, 2-sulfoethyl methacrylate and the like. Examples of the salt of the sulfonic acid group-containing compound in (B) and (D) include sodium salt, potassium salt, ammonium salt and the like. Among these, 2- (meth) acrylamide-2-methylpropanesulfonic acid and its salt, and styrenesulfonic acid and its salt are preferable, and 2-acrylamide-2-methylpropanesulfonic acid is preferable from the viewpoint of corrosion prevention and scale prevention. Acids (AMPS) and salts thereof are more preferred. These can be used alone or in combination of two or more.

Examples of the allyl ether compound in (C) include 3- (meth) allyloxy-2-hydroxy-1-propanesulfonic acid and a salt thereof, 3- (meth) allyloxy-1-hydroxy-2-propanesulfonic acid and its salt. Salt is mentioned. Examples of the salt of the allyl ether compound in (C) include sodium salt, potassium salt, ammonium salt and the like. Among these, 3- (meth) allyloxy-2-hydroxy-1-propanesulfonic acid and salts thereof are preferable from the viewpoint of corrosion prevention and scale prevention, and 3-allyloxy-2-hydroxy-1-propanesulfonic acid (3-allyloxy-2-hydroxy-1-propanesulfonic acid). HAPS) and salts thereof are more preferred, and sodium 3-allyloxy-2-hydroxy-1-propanesulfonate is even more preferred. These can be used alone or in combination of two or more.

Examples of the acrylamide compound in (D) include N, N-dimethylacrylamide, N-isopropylacrylamide, tert-butylacrylamide and the like. Among these, tert-butylacrylamide is preferable from the viewpoint of corrosion prevention and scale prevention. These can be used alone or in combination of two or more.

As (A), a polymer derived from one selected from acrylic acid and a salt thereof and a salt thereof are preferable from the viewpoint of further suppressing the decomposition of the sulfonated pyrene compound.

(B) includes a structural unit derived from at least one selected from acrylic acid and a salt thereof, and 2- (meth) acrylamide-2-methylpropanesulfonic acid and a salt thereof from the viewpoint of corrosion prevention and scale prevention. A polymer and a salt thereof containing a structural unit derived from at least one selected from, and a structural unit derived from at least one selected from acrylic acid and a salt thereof, and 2- (meth) acrylamide-2-methylpropanesulfon. A polymer and a salt thereof preferably containing a structural unit derived from at least one selected from an acid and a salt thereof and a structural unit derived from at least one selected from styrene sulfonic acid and a salt thereof, preferably acrylic acid and a salt thereof. A polymer and a salt thereof, which comprises a structural unit derived from at least one selected from the salt and a structural unit derived from 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and at least one selected from the salt. In addition, a structural unit derived from at least one selected from acrylic acid and its salt, a structural unit derived from at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and its salt, and styrenesulfonic acid and its salt. A polymer containing at least one structural unit selected from a salt and a salt thereof are more preferable, and a structural unit derived from at least one selected from acrylic acid and a salt thereof and 2-acrylamide-2- Further preferred are polymers and salts thereof that include a structural unit derived from at least one selected from methylpropanesulfonic acid and salts thereof.

(C) includes a structural unit derived from at least one selected from acrylic acid and a salt thereof from the viewpoint of corrosion prevention and scale prevention, and 3- (meth) allyloxy-2-hydroxy-1-propanesulfonic acid. And a polymer and a salt thereof containing a structural unit derived from at least one selected from the salt thereof, and a structural unit derived from at least one selected from acrylic acid and a salt thereof, and 3-allyloxy-2. More preferably, it is a polymer and a salt thereof containing a structural unit derived from at least one selected from −hydroxy-1-propanesulfonic acid (HAPS) and a salt thereof.

As (D), from the viewpoint of corrosion prevention and scale prevention, a structural unit derived from at least one selected from acrylic acid and a salt thereof, 2- (meth) acrylamide-2-methylpropanesulfonic acid and a salt thereof. It is preferable that the polymer and its salt contain a structural unit derived from at least one selected from, and a structural unit derived from tert-butylacrylamide, and a structure derived from at least one selected from acrylic acid and its salt. A polymer or salt thereof comprising a unit, a structural unit derived from at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and a salt thereof, and a structural unit derived from tert-butylacrylamide. preferable.

The arrangement of the structural units in the above (A) to (D) is not particularly limited, and may be any of a random copolymer, an alternate polymer, a block copolymer, and a graft copolymer. Further, the above (A) to (D) may be one kind alone or two or more kinds.

The polymers and salts thereof in (B) to (D) may have structural units derived from other monomers different from the respective structural units. The content thereof is preferably 50% by mass or less, more preferably 30% by mass or less, and more preferably 20% by mass or less, based on the total mass of the polymer containing each structural unit and its salt. Is more preferable.
Examples of the other monomers include a carboxylic acid compound, a monoethylenically unsaturated hydrocarbon compound, an alkyl ester of a monoethylenically unsaturated acid, a vinyl ester of a monoethylenically unsaturated acid, a substituted acrylamide compound, and an N-vinyl monomer. Examples thereof include one or more of a compound, a hydroxyl group-containing unsaturated monomer compound, a (meth) acrylic acid ester, an aromatic unsaturated monomer compound, and a sulfonic acid compound.

In the above (A) to (D), the polymer salt can be obtained, for example, by producing a polymer containing each structural unit and then neutralizing the polymer. It can also be obtained by polymerizing using a monomer salt (for example, acrylate) as a component derived from the structural unit of the polymer. The polymer salt thus obtained is not limited to a completely neutralized product of the polymer, and may be a partially neutralized product.
Examples of the polymer salt in the above (A) to (D) include alkali metal salts such as sodium salt and potassium salt, ammonium salt, amine salt and the like. As these salts, suitable ones can be appropriately selected and used according to the desired chemical effect and the cooling water system.

The (meth) acrylic acid-based polymer may be used alone or in combination of two or more. That is, as the (meth) acrylic acid-based polymer, the (meth) acrylic acid-based polymers (A) to (C) may be used alone, for example, with the (meth) acrylic acid-based polymer (A). Two or more types may be used in combination, such as in combination with (B).

Among the above (A) to (D), (B) and (C) are preferable from the viewpoint of further suppressing the decomposition of the sulfonated pyrene-based compound, and the structure derived from at least one selected from acrylic acid and a salt thereof. Derived from a polymer and a salt thereof containing a unit and a structural unit derived from at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and a salt thereof, and at least one selected from acrylic acid and a salt thereof. More preferably, a polymer and a salt thereof containing a structural unit and a structural unit derived from at least one selected from 3-allyloxy-2-hydroxy-1-propanesulfonic acid and a salt thereof.

The weight average molecular weight of the (meth) acrylic acid-based polymer and its salt is preferably 1,000 to 100,000, more preferably 2,000 to 50,000, and 5,000 to 30, It is more preferably 000, and even more preferably 8,000 to 20,000. When the weight average molecular weight is within the above range, it is possible to suppress the decomposition of the sulfonated pyrene compound.
The weight average molecular weight is a standard polystyrene-equivalent weight average molecular weight obtained by gel permeation chromatography (GPC).

The content of the (meth) acrylic acid-based polymer in the water treatment agent is not particularly limited, but is preferably 1% by mass or more, more preferably 3 from the viewpoint of suppressing the decomposition of the sulfonated pyrene-based compound. It is preferably 40% by mass or more, more preferably 4% by mass or more, and preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 25% by mass or less from the viewpoint of ease of handling and viscosity.
The content of the (meth) acrylic acid-based polymer in the active ingredient of the water treatment agent is preferably 80% by mass or more, more preferably 90% by mass or more, still more preferably, from the viewpoint of suppressing the decomposition of the sulfonated pyrene-based compound. Is 95% by mass or more, and more preferably 99% by mass or more.
In the present invention, the active ingredient means a component obtained by removing a solvent such as water from a water treatment agent.

When the water treatment agent of the present invention is added to the cooling water system, the cooling water system has (from the viewpoint of suppressing the decomposition of the sulfonated pyrene compound and exerting at least one effect selected from corrosion prevention and scale prevention. Meta) It is preferable to add the acrylic acid-based polymer so that the concentration is 0.1 mg / L or more and 100 mg / L or less, more preferably 0.5 mg / L or more and 50 mg / L or less, and further preferably 1 mg / L. It is 10 mg / L or less.

<Sulfated pyrene compound>
The sulfonated pyrene compound is a fluorescent substance, and fluoresces the concentration of the (meth) acrylic acid-based polymer derived from the water treatment agent and other effective components contained in the cooling water to which the water treatment agent of the present invention is added. It is a tracer substance for indirect measurement by the photometric method.
As the sulfonated pyrene-based compound, various compounds can be used as long as they can function as a tracer substance for the (meth) acrylic acid-based polymer contained in the water treatment agent and other effective components. For example, pyrene sulfonic acid. Alternatively, it is preferable to use the salt thereof. The pyrene sulfonate is usually an alkali metal salt such as a sodium salt. Pyrene sulfonic acid and a salt thereof can be used in combination as appropriate.

The pyrene sulfonic acid or a salt thereof is not particularly limited as long as the number of substitutions of the sulfo group or the sulfonic acid base is chemically acceptable, respectively, but from the viewpoint of availability, the sulfo group or the sulfonic acid is used. A four-base substituted product, that is, pyrenetetrasulfonic acid or a salt thereof, is preferable, and 1,3,6,8-pyrenetetrasulfonic acid or a salt thereof (for example, a tetrasodium salt) is more preferable. Pyrenetetrasulfonic acid and a salt thereof can be used in combination as appropriate.

The content of the sulfonated pyrene compound in the water treatment agent is not particularly limited, but is preferably 0.001% by mass or more, more preferably 0.005% by mass, from the viewpoint of stable concentration control. % Or more, more preferably 0.008% by mass or more, preferably 1% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.1% by mass or less from the viewpoint of cost control.
The content of the sulfonated pyrene compound in the active ingredient of the water treatment agent is preferably 0.005% by mass or more, more preferably 0.025% by mass or more, still more preferably 0.025% by mass or more, from the viewpoint of stably carrying out concentration control. It is 0.04% by mass or more, preferably 5% by mass or less, more preferably 2.5% by mass or less, still more preferably 0.5% by mass or less from the viewpoint of cost control.

When the water treatment agent of the present invention is added to the cooling water system, the concentration of the sulfonated pyrene compound in the cooling water system should be 0.01 mg / L or more and 10 mg / L or less from the viewpoint of stable concentration control. It is preferably added, more preferably 0.02 mg / L or more and 5 mg / L or less, still more preferably 0.05 mg / L or more and 3 mg / L or less.

The pH of the water treatment agent of the present invention can usually be adjusted by adding an aqueous solution of a mineral acid such as hydrochloric acid, sulfuric acid or nitric acid, or an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. can.

The water treatment agent of the present invention may contain an active ingredient other than the (meth) acrylic acid-based polymer and the sulfonated pyrene-based compound, depending on the purpose of use thereof and within the range not interfering with the effects of the present invention. .. For example, other additives other than the (meth) acrylic acid-based polymer, such as anticorrosion agents, anti-scale agents, fungicides, algae-killing agents, dispersants, slime control agents, release agents, and antifoaming agents may be used in combination. ..

Hereinafter, the present invention will be described in more detail, but the present invention is not limited to the following examples.

[(Meta) acrylic acid polymer]
Details of the polymer used as the (meth) acrylic acid-based polymer in the following examples are shown below.
In addition, the structural unit of the polymer in the following is represented by the component name (monomer) from which it is derived. AA represents acrylic acid, AMPS represents 2-acrylamide-2-methylpropanesulfonic acid, and HAPS represents sodium 3-allyloxy-2-hydroxy-1-propanesulfonic acid.
(Meta) acrylic acid-based polymer (i): "Accusol 587" (AA / AMPS copolymer, manufactured by Dow Chemical Co., Ltd., monomer ratio AA: AMPS = 79: 21, weight average molecular weight: 11,000)
(Meta) acrylic acid polymer (ii): "GL386" (AA / HAPS copolymer, manufactured by Nippon Shokubai Co., Ltd., monomer ratio AA: HAPS = 80:20, weight average molecular weight: 9,310)

[Sulfated pyrene compound]
The compounds used as sulfonated pyrene compounds in the following Examples and Comparative Examples are shown below.
・ 1,3,6,8-Pyrenetetrasulfonic acid tetrasodium salt (manufactured by SpectraColors Corporation)

<Example 1>
The concentration of the (meth) acrylic acid-based polymer (i) in pure water is 20% by mass, and the concentration of 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt is 0.01% by mass. The (meth) acrylic acid-based polymer (i) and the 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt were added and mixed so as to prepare an aqueous solution. Sulfuric acid or sodium hydroxide was added to the aqueous solution to obtain a water treatment agent having a pH of 4.0, 6.4, and 11.1.
For the water treatment agent having each pH immediately after production, the sulfonated pyrene-based compound is excited with light of 365 nm using a spectrofluorometer "opti-check" (manufactured by TURNER DESIGN), and then fluorescence of 400 nm. The fluorescence intensity of the wavelength (hereinafter referred to as "reference fluorescence intensity") was measured.

Subsequently, 100 mL of the water treatment agent having each pH was put into separate polyethylene containers having a capacity of 100 mL, and the polyethylene container containing the water treatment agent was exposed to direct sunlight by leaving it outdoors in fine weather. .. One hour after the start of exposure, the fluorescence intensity of the fluorescence wavelength of 385 nm was measured for the water treatment agent having each pH after exposure using the spectrofluorescence meter in the same manner as described above, and the fluorescence with respect to the reference fluorescence intensity was measured. The residual intensity (fluorescence intensity of the water treatment agent after 1 hour exposure / reference fluorescence intensity × 100: unit%) was determined. In the present invention, the closer the residual ratio of the fluorescence intensity to the reference fluorescence intensity is to 100%, the more the decomposition of the sulfonated pyrene compound has not progressed.
In the same manner as above, 100 mL of the water treatment agent having each pH is placed in separate polyethylene containers, and the polyethylene container containing the water treatment agent is exposed to direct sunlight by leaving it outdoors in fine weather for 3 hours. For the water treatment agent, the residual ratio of the fluorescence intensity with respect to the reference fluorescence intensity (fluorescence intensity of the water treatment agent after exposure for 3 hours / reference fluorescence intensity × 100: unit%) was determined.
The results are shown in Table 1, and the change over time in the residual fluorescence intensity (%) is shown in FIG.

<Example 2>
The same applies to Example 1 except that the (meth) acrylic acid-based polymer (ii) is used instead of the (meth) acrylic acid-based polymer (i) and the pH of the water treatment agent is set to 4.1 and 10.8. Then, the reference fluorescence intensity of the water treatment agent having each pH, the fluorescence intensity of the water treatment agent after 1 hour exposure, and the fluorescence intensity of the water treatment agent after 3 hours exposure were measured, and the residual fluorescence intensity was obtained. rice field.
The results are shown in Table 1, and the change over time in the residual fluorescence intensity (%) is shown in FIG.

<Comparative Example 1>
In Example 1, polymaleic acid "Belclene272" (manufactured by BWA, weight average molecular weight: 1,304) was used instead of the (meth) acrylic acid-based polymer (i), and the pH of the water treatment agent was 6.2 and 11. In the same manner except that it was set to 1., the reference fluorescence intensity of the water treatment agent having each pH, the fluorescence intensity of the water treatment agent after 1 hour exposure, and the fluorescence intensity of the water treatment agent after 3 hours exposure were measured. Then, the residual fluorescence intensity was determined.
The results are shown in Table 1, and the change over time in the residual fluorescence intensity (%) is shown in FIG.

As is clear from Table 1 and FIGS. 1 to 3, a water treatment agent containing a sulfonated pyrene-based compound and a (meth) acrylic acid-based polymer and having a pH of more than 2 and less than 12 suppresses the decomposition of the sulfonated pyrene-based compound. You can see that.

Claims (2)

A water treatment agent used in cooling water systems.
A polymer and a salt thereof, which comprises a structural unit derived from at least one selected from acrylic acid and a salt thereof, and a structural unit derived from at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and a salt thereof. And a polymer containing a structural unit derived from at least one selected from acrylic acid and a salt thereof, and a structural unit derived from at least one selected from 3-allyloxy-2-hydroxy-1-propanesulfonic acid and a salt thereof. And at least one selected from its salts,
Contains 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt and
The content of the 1,3,6,8-pyrenetetrasulfonic acid tetrasodium salt is 0.001% by mass or more and 0.5 % by mass or less .
A water treatment agent having a pH of 5-8. A polymer and a salt thereof containing a structural unit derived from at least one selected from the acrylic acid and a salt thereof, and a structural unit derived from at least one selected from 2-acrylamide-2-methylpropanesulfonic acid and a salt thereof. , And a structural unit derived from at least one selected from the acrylic acid and its salt, and a structural unit derived from at least one selected from 3-allyloxy-2-hydroxy-1-propanesulfonic acid and its salt. The water treatment agent according to claim 1, wherein the content in at least one active ingredient selected from the contained polymer and a salt thereof is 80% by mass or more.

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